Method for recovering gallium value from aqueous solution of crude aluminum salt

Abstract

An efficient method is proposed for the recovery of a trace amount of a gallium value from an aqueous solution containing a large amount of an aluminum salt as the principal solute as in the solution which is prepared by dissolving the precipitates obtained by neutralizing a Bayer's solution with carbon dioxide in hydrochloric or sulfuric acid. The method comprises admixing the aqueous solution with a water-soluble ferrocyanide compound, e.g., sodium ferrocyanide, as a precipitant of gallium ferrocyanide in such a controlled small amount as not to exceed 2.5 times by moles of the gallium ions in the starting solution so that coprecipitation of aluminum ferrocyanide is minimized.

What is claimed is: 
     
       1. A method for the recovery of a gallium value from an aqueous solution produced by the Bayer process containing an aluminum salt as a principal solute and gallium ions which consists of: (a) admixing the aqueous solution with a ferrocyanide compound soluble in water to selectively precipitate the gallium value in the form of gallium ferrocyanide, the amount of the ferrocyanide compound being in the range from 1.0 to 2.5 times the moles of the gallium ions contained in the aqueous solution when the concentration of gallium in the aqueous solution is larger than 50 mg/liter and at least equimolar to the gallium is contained in the solution but not exceeding such an amount to give a concentration of about 1.8×10 -3  mole/liter thereof in the solution when the concentration of gallium in the aqueous solution does not exceed 50 mg/liter; and   (b) separating the precipitate of the gallium ferrocyanide from the solution.   
     
     
       2. The method for the recovery of a gallium value from an aqueous solution containing an aluminum salt as a principal solute and a trace amount of gallium ions as claimed in claim 1 wherein the ferrocyanide compound soluble in water is sodium ferrocyanide.